Diesel engine



Aug. 16, 1938.

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Filed Oct. 19. 1936 J. J. EHRAT DIESEL ENGINE FU ELPUMPWITH DELIVERYVALVE'.

REMOVED 2 Sheets-Sheet l VC'OMPEESSELD GAS OR, INJECTION AR. LINE,

FUEL LINE.

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Gttornegs Aug, 16, 1938.v -.J J. l-:HRAT

DIESEL ENGINE Filed oct. 19..19se

2 Sheets-Sheet 2 KM@ dm- Gttomegs Patented Aug. 16, 1938 iiNiTE STATESATENT OFFICE DIESEL ENGINE and .lean J; Ehrat,

Nordberg Manufactu kee, Wis., a corporation of Wisconsin ApplicationOctober 19,

7 Claims.

es to Diesel engines and for controlling fuel injechas utility inconnection gines of the type in which the lift of the air injecisintended chiefly for use according to the methods d in the patents toNordberg, 10,

1932, and No. 1,962,282, anical control for such enclaimed in Patent No.

1,949,577, March 6, 1934.

Generally stated i5 an ignition charge of by combustible gas underpressure.

into highly compressed air i the cycle involves injecting n the workingspace fuel oil, which is sprayed The gas serves as the motive fuel, theoil preferably being insuiicient in gine. Regulation is h of gas foreach injecti quantity to operate the enad by varying the lift lofsequently the quantity on.

' Because of the small valve lift even at full load, mechanical meansfor varying the valve lift though entirely operative, are sometimeserratic in action particularly at light loads. In an effort to improvethe control characteristics recourse was had to hydraulic actuation.'I'he hydraulic actuation and control mechanism hereinafter describedhas been found to have remarkably precise and uniform operatingcharacteristics, and has the commercial advantage that a standard typeof Diesel fuel pump can be used (with minor modification) as a majorcomponent.

This embodiment wil l now be described in connection with theaccompanying drawings, in

Fig. 1 is an end elevation of a Diesel engine embodying the invention.

showing the fuel oil for a single cylinder be actuated by cams on of aportion of Fig. 1

Fig. 3 is a vertical axial section on an enlarged scale through thecylinder head, the fuel injection valve and the hydraulic means foractuating such valve.

Fig. 4 is a. section'on the line 4 4 of Fg.'3.

Fig. 5 is a section on the line 5 5 of Fig. 3.

Fig. 7 is a vertical impulse pump, showin shaft.

Fig. 8 is a perspective 5 of Fig. 7, showing spill Fig. 6 is a sectionon the line 6-6 of Fig. 3.

axial section through the g its relation to the cam v iew of the pump.plunger back control.

1936, serial No. 106,442 (c1. 12s-s3) Fig. 9 is a fragmentary Viewsimilar to a portion of Fig. 7 and showing the check valve used in thefuel pump and omitted from the impulse pump, the two being otherwisesimilar.

Generally stated the needle valve of the Diesel 5 engine is actuated byahydraulic plunger to which impulses are delivered by a pump whosedelivery is Varied by an adjustable spill back. 'I'he spill back opensto connect the working space of the pump with its -supplypassage at avariable 10 point in each working stroke. Since the pump as here usedhas no discharge valve, when the spill back opens back flow occurs fromthe discharge line, and hence from the hydraulic plunger to the intakeof the pump. To prevent heating and l5 to stabilize temperatureconditions in the discharge line, the latter is water jacketed.Lubricating oil is used as the hydraulic pressure fluid. To guardagainst accumulation of air in the discharge line, a small quantity ofoil is bled each 2O working stroke from the pump discharge to anelevated sump from which the pump intake is fed. Thus the oil is slowlycirculated in a closed path and progressive accumulation of air in thedischarge line is precluded. Because of the high 25 pressures used andthe high operative speed the presence of even small amounts of air inthe oil under pressure would have a seriously disturbing e'ect. Mostoils carry some occluded air, but if any is freed in the discharge pipeit is carried 30 away by the circulatory flow, so that an objectionableair volume cannot develop even by slow accretion.

Referring rst to Fig. 1, II represents, the base of the engine. I2represents one of the cylinders, 35 I3 is a cylinderhead, I4 representsthe exhaust manifold and I5 the scavenging air manifold. The inventioncan be applied to either single or multiple cylinder engines of eithertwo or four stroke cyclefit being understood that there be. 40

a separate fuel pump and impulse pump for each cylinder, the variouspumps being driven in proper timed relation by suitably spaced cams onasingle cam shaft. Since this involves mereduplication of features ofthe invention, it is not deemed 45 necessary to illustrate all thecylinders of a multi ple cylinder engine.

The lobe I6 at the left of the crank case is the cam shaft housing andit will be observed that the fuel pumps and impulse pumps are mounted 50on top of this housing so as to coact with a series of cams `on the camshaft.

'Ihe device indicated at I0 is a speed governor, here assumed to be ofthe well known Woodward type. So far as is essential to the presentinvention, it suffices to point out that in response to en-V gine speedvariation the Woodward governor causes the arm I1 to swing angularly.

Referring now to Figs. 1 and 3, there is mounted in the center of headI3, the bonnet I8 of the fuel injection valve. rIhis bonnet includes atubular housing I9 which extends through the head and seals on ashoulder 20. It is held down by the flange 2| which is retained by thesame studs which hold bonnet I8 as clearly shown in Fig. 3.

Mounted within housing I9 is the tubular shell 22 externally grooved asindicated at 23 to permit downward flow of fuel oil between shell 22 andhousing I9. A spring 24 holds the shell 22 downward.

The needle Valve generally indicated by the numeral 25 extends freelythrough shell 22 and seats at 26 in housing |9. Below the seat 26 andheld to housing I9 by a sleeve nut clearly shown in Fig. 3 is thenozzle-forming ame plate 21. Housing I9 has a lateral extension 28 towhich the gas and oil connections are made, the gas passage beingindicated at 29 and the oil passage at 3|) (see Figs. and 6) Oilsupplied through passage 30 iiows through grooves 23 to the spaceimmediately above seat 26. When needle valve 25 lifts, combustible gasentering under high pressure through passage 29 flows through shell 22around the stem of valve 25 and sprays the oil through flame plate 21into the -working space of the engine. The gas must be under a pressurehigher than the compression in the working space and may be supplied bya compressor (not shown) forming part of the engine (as is usual), or bymeans independent of the engine. All that is required is a source of gasunder su'icient pressure.

The stem of .valve 25 passes through a packing gland 3| and carries atits upper end a cross head 32 which is guided for vertical reciprocatorymotion in the housing 33. This last is a part of bonnet I8 and issupported thereon by the spaced members 34. An adjustable coilcompression spring 35 urges cross head 32 downward, i. e. in a valveclosing direction.

The parts so far described do not differ markedly from valves heretoforeused in air injection Diesel engines.

A bifurcated lever 36 is pivoted at 31 on the upstanding members 34 andcarries two cylindrical thrust blocks 38 which underlie a hardened steelthrust ring 39 xed on stem of valve 25. To operate the lever 36, andconsequently the valve 2,5, a pressure motor, whose cylinder isgenerally indicated at 4|, is mounted on the cylinder head I3. Slidablein the cylinder 4| is a free plunger 42 which is subject on its lowerend to hydraulic pressure communicated through the connection 43. Theplunger 42 is circumferentially grooved to minimize leakage and is inthrust engagement at its upper end with a push rod 44 which engages aroller 45 on the lever 36. A coil tension spring 46 draws the lever 36downward. Mounted near the lower end of the cylinder 4| is a choke orbleed fitting 41 which is held in place by the screw plug 48. This chokefitting permits very slow flow from the upper end of the passage 43 to'apipe 49 which leads to the elevated sump 5| (see Fig. 1). This sumpfurnishes the oil to the hydraulic pressure system by way of valve 52and pipe 53 and serves also as a gas separation chamber. 'I'he elbow 54is a drain connection for such oil as may leak past the piston 42 andpush rod 44. It may be piped to any suitable point, such drain pipingnot being shown in the drawings.

To develop timed pressure impulses to actuate the piston 42, use is madeof a pump essentially identical with the fuel injecting pumps commonlyused in Diesel engines. It comprises a spill back measuring pump hereshown as of the type manufactured by the United American BoschCorporation. Its construction is indicated in Figs. k7 and 8.

In Figure 7, 55 represents the engine cam shaft which in a two cycleengine would be driven at crank shaft speed and in a four vcycle engine4would be driven at half crank shaft speed. Shaft 55 carries a cam 56 inthrust engagement with the roller 51 carried by the cross head 58. Thespring 59 forces the cross head downward and the key and spline 6| holdit against rotation. The element 62 acts as a combined spring seat anddiverter for any oil which might leak downwardly from the fuel pump. Adrain connection (not shown) is provided for such oil. Where the pump ishandling lubricating oil such diversion is not particularly important.

The stem 63 of the cross against the cup-shaped cross head 64 of thefuel pump, generally indicated at 60. The stem carries an umbrella-likecap to direct oil to diverter 62. Cross head 64 is urged downward by aspring which is indicated at 65. The spring reacts upon a disk 66 whichembraces a head formed on the lower end of the pump plunger 61. Theplunger 61 works in a fixed bushing or sleeve 68 which has an inlet port69, and on the opposite side a spill back port 10. The plunger 61 has arecess 1| provided with one spiral margin 12, so formed that rotation ofthe plunger on its longitudinal axis will vary the time in the workingstroke at which the working space 13 above the plunger 61 is connectedthrough recess 1| withthe spill back port 10. As the plunger 61 movesupward, it first displaces oil from the working space through the pipeconnection 14 to the passage 43, heretofore described and then opens thespill back port to the intake.

The pipe 14 is jacketed as indicated at 15, there being inletanddischarge cooling water connections, one of which appears at 16 inFig. 3, and the other of which appears at 11 in Fig. '1. The purpose ofthis is to establish stable temperature conditions in the outlet, andprevent the development of heat therein. The piston displacements aresmall, the pressures are high, and ow through the connecting passages israther rapid. While the water jacket may not be necessary in head reactsin thrust .all cases, it is considered a desirable adjunct.

The hydraulic liquid, conveniently lubricating oil, is brought to thesupply passage 69 from the elevated sump 52 by way of pipe 53 which isconnected to the pump as indicated at 18. To rotate the vplunger 61 andthus change the point in the working stroke at which the spill backcommences a rotary sleeve 19 bifurcated at its lower end is provided.The bifurcated lower end straddles the cross plate 8| fast on theplungerstem, permitting reciprocation of the plunger but controlling itsangular position. The sleeve 19 is angularly adjusted by the toothedsector 82 which meshes with rack teeth on a bar 83 slidably mounted inthe body of the pump.

Referring now to Fig. 1, the bar 83 is connected by bell crank 84 andlink 85 with the arm |1 on the governor. In a multi-cylinder engine thebell crank 84 would be part of a rock shaft extending along the engineand connected similarly to the adjusting rods of all the impulse units,of which there would be one for each cylinder.

As the governor responds to increasing speed it moves the arm il and therod 83 in a direction to hasten the spill back and thus reduce the liftof the needle valve 25. v

It is necessary to supply fuel oil through the connection 30 to theneedle valve. To perform this function a second pump, substantiallyidentical with that shown in Fig. '7, is used. 'I'his pump is indicatedin Fig. 2 at 86. It may have and conveniently would have an adjustingmember 8l, but this adjusting member is not operated by the governor. Onthe contrary it is manually set and then locked in position. The pump 86delivers fuel oil through the pipe 88 to the connection 30.

Unlike the impulse device shown in Fig. 7 the fuel pump 86 has above theWorking space' of the pump and between it and the pipe 88, a combinedcheck valve and anti-dribbling device 88 characteristic of the Boschfuel feed pump and for which no novelty is here claimed. The device 89consists essentially of a check valve attached to a small piston beneathit, the piston being provided With bypass grooves. A compression spring9i urges the valve toward its seat, preventing'back .-flow of the oilthat has been discharged on the working stroke. This valve and v springare omitted from the impulse unit, as indicated in Fig. 7, because backflow is an important factor in the use of the pump as an impulse device.

The operation of the mechanism can now be traced. The cam which operatesthe fuel pump 86 is so timed that it will complete delivery of ameasured quantity of oil to the space above seat of needle valve 25,shortly before the lift of the valve commences. The cam which operatesthe plunger in the impulse device 60 is properly timed with reference tothe desired time of lift of the needle valve 25. It is given the usualslight lead with reference to the head end dead point of the enginepiston and a slight additional lead to compensate for a lag factor inthe response of the piston 42. 'Ihe lag is slight and has been found tobe so nearly uniform as to introduce no material disturbing factor` Itis present, however, and should be compensated for.

When the piston 6l descends it draws in oil fed through the connection53 and port 68. On its ensuing upward stroke it displaces this oilthrough the pipe lil, and this oil arriving through the port i3 forcesthe piston 42 upward and lifts the needle valve 25. 'I'his actioncontinues until the spill back port opens, the point of opening ybeingdetermined by the angular position of the piston 61 as alreadydescribed. As soon as the spill back port i opens back flow occurs fromthe space below the ply connection I8 and pipe 53.

piston 132 through the port 43 and pipe lid Aand thence through thespill back port il to the sup- It follows that the prime purpose of theplunger 6l is to deliver an impulse to the 'piston i2 through oil underpressure and then dissipate this pressure at some chosen point in theWorkingstroke of the plunger 67, causing descent of the piston l2 andthe related needle valve 25. The governor controls the duration of thelift impulse. serves each stroke to bleed from the upper end of theconnection lll, i3 ``a`\minute quantity of oil. Any air occluded in theoil would tend to accumulate near the upper end of this connection, andthe function of the bleed port is to dissipate this air as it i's freedand prevent its accumulation. In consequence there is a minutecontinuous circulation of oil in a closed circuit but the major portionof the oil flow is reversed in each cycle.

The device has been found to give precise tim- The leak port il meansfor varying the point in ing and a smoothly graduated regulation of liftthroughout the entire load vrange of the engine. Some idea of theprecision required can be gained from the fact that in tests with athree cylinder 17 by 25" Diesel engine, using this type of fuel control,the valve lift never exceeded 0.044 and the minimum of lift was of theorder. of 0.008". 'Ihe improvementin regulation as compared to astrictly mechanical control of the lift was noticeable throughout theload range and particularly noticeable in the low load ranges in whichsmall lifts are encountered.

In certain types of air injection Diesel engines control of the lift ofthe needle valve enters into the engine regulation. In such engines thehydraulic variable lift needle valve actuating mecha`nism hereindisclosed would be useful.

While I have shown one particular commercial type of spill back valve,and prefer it, .other types are known, and might be substituted withoutdeparture from the spirit of the invention. In certain cases it may not-be necessary to use the bleed port 4l. Its omission involves nomaterial change in operative principle. The Water jacket 'l5 on thepressure pipe may also be omitted Without change of principle. Variousother changes within the spirit of the invention may be made by theexercise of mechanical skill, and the possibility of maln'ng suchchanges is contemplated.

What is claimed is:-

l. The combination with an lengine of the Diesel type having a workingspace; of a nozzle for injecting fuel into said space; a normally closedvalve controlling iiow through said nozzle; means for supplying chargesof liquid fuel to said nozzle in advance of said valve; means forsupplying gas under pressure to said nozzle in advance of said valve; ahydraulic pressure motor for opening said valve; and means fordelivering timed pressure impulses to said motor and comprising areciprocating displacement plunger device driven in timed relation bysaid engine and having a liquid intake and a spill back opened to saidintake at a point in the displacement stroke of said plunger.

2. The combination with an engine of the Diesel type having a Workingspace; of :i nozzle for injecting fuel into said space; a normallyclosed valve controlling iiow through said nozzle; means for supplyingcharges of liquid fuel to said nozzle in advance of said valve; meansfor supplying gas under pressure to said nozzle in advance of saidvalve; a hydraulic pressure motor for opening said valve; means fordelivering timed pressure impulses to said motor vand comprising areciprocating displacement plunger device driven in timed relation bysaid engine and having a liquid intake and a spill back open to saidintake at a point in the displacement stroke of said plunger; and meansfor varying the point in the displace'- ment stroke at which said spillback opens.

3. The combination with an engine of the Diesel type having a workingspace; of a nozzle for injecting fuel into said space; a normally closedvalve controlling flow through said nozzle; means for supplying chargesof liquid fuel to said nozzle in advance of said valve; means forsupplying gas under pressure to said nozzle in advance of said valve; ahydraulic pressure motor for opening said valve; means for deliveringtimed pressure impulses to said motor and comprising a reciproeatingdisplacement plunger device driven in timed relation by said engine andhaving a liquid intake and a spill back opened to said intake at a pointin the displacement stroke of said plunger;

the displacement stroke at which said spill back opens; and a governorresponsive to engine speed connected to control the last named means.

4. The combination with an engine of the Diesel type having a workingspace; of a nozzle for injecting fuel into said space; a normally closedvalve controlling flow through said nozzle; means for supplying chargesof liquid fuel to said nozzle in advance of said valve; means forsupplying gas under pressure to said nozzle in advance of said valve; ahydraulic pressure motor for opening said Valve; impulse means connectedto deliver fluid pressure impulses to said motor and comprisingreciprocating plunger and coacting cylinder provided with a liquidintake and interacting spill-backmeans for returning liquid to saidintake', the time of opening of said spill-back means in each workingstroke being controlled by the relative angular positions of the plungerand cylinder; and means for varying such angular position.

5. The combination with an engine of the Diesel type having a workingspace; of a nozzle for injecting fuel into said space; a normallyAclosed valve controlling ilow through said nozzle; means for supplyingcharges of liquid fuel to said nozzle in advance of said valve; meansfor supplying gas under pressure to said nozzle in advance of saidvalve; a hydraulic pressure motor for opening said valve; impulse meansconnected to deliver fluid pressure impulses to said motor andcomprising reciprocating plunger and coacting cylinder provided with aliquid intake and interacting spillback means for returning liquid tosaid intake, the time of opening of said spill-back means in eachworking stroke being controlled by the relative angular positions of theplunger and cylinder; means for varying such angular position; and agovernor responsive to engine speed and connected to actuate thelast-named means.

6. In a Diesel `engine the combination of fuel injecting valve; ahydraulic pressure motor for actuating said valve; means driven by saidengine for developing hydraulic pressure impulses in timed relation tothe operation of the engine; means for confining a liquid through whichsaid impulses are transmitted to said motor; and means for regulatingthe temperature of said liquid.

7. In a Diesel engine the combination of fuel injecting valve; ahydraulic pressure motor for actuating said valve; means driven by saidengine for developing hydraulic pressure impulses in timed relation tothe operation of the engine; means for confining a liquid through whichsaid impulses are transmitted to said motor; and a cooling jacket forcontrolling thek temperature of said liquid.

- JEAN J. EHRAT.

